This invention relates to the general field of agriculture, and specifically to means for reliably causing the flow of particulate material such as feed from a bin, of circular transverse section about a vertical axis, having a conical bottom converging downwardly to a central discharge chamber for subsequent removal of the material therefrom by conventional means such an auger conveyor.
Bins of the type just described, supported on peripheral legs of various sorts, are very common in agricultural communities. They are relatively easy to erect, relatively inexpensive, and conveniently filled using widely available equipment, and they give good protection to their contents against inclemencies of weather and attacks by rodents. Their principle defect lies in the difficulty frequently encountered in extracting their contents when it is desired to do so. The processes of settling and aging, aided by minute movement of particles according to temperature changes, frequently produces a condition known as bridging, in which material at the bottom of the bin forms a natural arch supporting the weight of the material above it, and resistent even to considerable impact of shovels and the like applied against the outside of the bin.
Bridging takes place most readily at the very bottom of the bin where the diameter is smallest, so that the span of the natural arch is the least: it seldom occurs when the span must be substantially a major portion of the bin diameter itself.
Numerous attempts have been made to overcome this difficulty, the most common being the provision of a traveller shaft driven through a universal joint by a central vertical power shaft to move around within the bin bottom and undercut any natural arching. For a full bin the amount of power required to move such a shaft transversely through the material is very great, and there is a considerable tendency for the traveller shaft to simply rotate about its own axis without moving around the bin axis, thus loosening for discharge only a small amount of the material in the bin. In attempts to enforce a positive drive between a coggged wheel at the outer end of the traveller shaft and a cogged track surrounding the conical bottom at its top has also been made, but this exacerbates the problem by multiplying both the power required of the drive motor and the required strength of all the components used.
It has also been found that even when released into the discharge space, material has a tendency to pack or bridge therein, so that an unloading auger is fed no material to discharge.